AD7943/AD7945/AD7948

REV. B

–9–

AD7943 PIN FUNCTION DESCRIPTIONS

Pin Mnemonic

Description

DAC current output terminal 1.

DAC current output terminal 2. This should be connected to the AGND pin.

AGND

This pin connects to the back gates of the current steering switches. In normal operation, it should be connected

to the signal ground of the system. In biased single-supply operation it may be biased to some voltage between

0 V and the 1.23 V. See Figure 11 for more details.

STB1

This is the Strobe 1 input. Data is clocked into the input shift register on the rising edge of this signal.

STB3

must be high. STB2, STB4 must be low.

LD1, LD2

Active low inputs. When both of these are low, the DAC register is updated and the output will change to

reflect this.

SRI

Serial Data Input. Data on this line will be clocked into the input shift register on one of the Strobe inputs,

when they are enabled.

STB2

This is the Strobe 2 input. Data is clocked into the input shift register on the rising edge of this signal.

STB3 must be high. STB1, STB4 must be low.

STB3

This is the Strobe 3 input. Data is clocked into the input shift register on the falling edge of this signal. STB1,

STB2, STB4, must be low.

STB4

This is the Strobe 4 input. Data is clocked into the input shift register on the rising edge of this signal.

STB3

must be high. STB1, STB2 must be low.

DGND

Digital Ground.

CLR

Asynchronous CLR input. When this input is taken low, all 0s are loaded to the DAC latch.

Power supply input. This is nominally +5 V for Normal Mode Operation and +3.3 V to +5 V for Biased

Mode Operation.

DAC reference input.

DAC feedback resistor pin.

AD7945 PIN FUNCTION DESCRIPTIONS

Pin Mnemonic

Description

DAC current output terminal 1.

AGND

internally to this point.

DGND

Digital Ground.

DB11–DB0

Digital Data Inputs.

CS

Active Low, Chip Select Input.

WR

Active Low, Write Input.

Power supply input. This is nominally +5 V for Normal Mode Operation and +3.3 V to +5 V for Biased Mode

Operation.

DAC reference input.

DAC feedback resistor pin.